Process of removing zinc from zinc-coated material.



UNITED QFFIQE.

JOSEI' WEBER, {OF nssEN-on-THE-nni-ra, GERMANY, ASSIGNOR TOI-IGOLDSCI-IMIDT nnrmmne oomrm, or NEW roan, n. r, A oonronarron or NEW JERSEY.

rnoonss-o'r nnmovrnszrno anon ZINC-COATED MA ERIAL.

11,122,340. No Drawing,

To all :whom it moj concern vBe it known that I, JosEF WEBER, a subect of the 'King of Prussia, (jerman Emperor, and a resident of Essen-on-the-Ruhr,

"in the German Empire, have invented a new and useful Process of Removing Zinc from Zinc-Coated lllateriahof which the followmg s an exact specification.

My invention relates .to a process of removing zinc from zinc-coated material, es

pecially zinc-coated iron in the form of sheet material, and the main object of the invention is to effect a more perfect separa.

tion' of the zinc from the other material more economically than has heretofore been possible.

Theprincipal material from which it has for a long time been desirable to recover zinc in" as pure a stateas possible is zinccoated ironin sheet forml Many efforts have been made heretofore to remove zinc from zinc-coated material for the purposeof recovering the zinc in solution and the other material in the form of black sheet scrap. In .all of the processes that have been proposed for this purpose however, the great drawbacks have been that in addition tolthe 'zinc a considerable amount of the iron has been dissolved by the reagent used and-that'the black sheet scrap is left by the reagent in such condition that it afterward becomes considerably corroded. Because of this action of the reagent on the iron much ofthe solution was wasted and it was very troublesome, expensive and attended with great .losses of the zinc content to remove the' iron' from such solution, as

the precipitated iron, even though very carefully washed would always contain a considerable amount of zinc. obtained bythe processes heretofore practised for recovering 'zinc from zinc coated material have always contained about 20 per cent. of zinc and from 5 to 7 per cent.

The present invention is designed to avoid all' the aboi e recited drawbacks which have heretofore attended the recovery of zinc from such material, and its essential feature is the employment of a solvent of.

zinc which has no acid reaction or is preferably neutral or even strongly bas1c and 1s substantially not a solvent of iron. Such a solvent can not be hydrochloric acid or any other acid solution that will readily attack Specification of Letters Eatent.

The solution Patented Dec. 29, 19142.

Application filed June 25, 1910. Serial no. 568,795.

I iron. {It is preferably a neutral or basic solution chlorid of zinc. Such asolution of chlond of, ZlIlC possesses the propeny of dissolving only the zinc presentin thescrap and-does not attack the iron on which the zinc forms a coating. This property is .made use of in the present process to effect a more perfect separation of the zinc from" the iron of zinc scrapthan has been possible with ,the acid solutions heretofore used. Theoretically'chlorid of zinc should contain alittle 0V61' '26 per cent. of chlorin'to a little less than 24 per cent. of zinc, this b eing'the'. ratio ofzinc and chlorinin the ordinary solution of chlorid of zinc. According to the present invention a solution .of chlorid oiv zincis' used in which the ratio of chlorin to the zinc is about 1 per cent.

less than in 'the'theoretical formula. By so varying the ratio of chlorin to .the zinc probably basic chlorids of "zinc will'be formed. Such a solution as this will dissolve only the zinc present in the scrap and will not substantially attack the iron from which the zinc is to be removed. .W'hen the 'scrap is subjected to the action of such a basic solution of chlorid of zinc the reaction may be continued until the solution is enriched by the zinc to such an extent that the resulting solution isbasic to the extent of three or even four per cent.- By employing suclra solution only a small quantity of iron is dissolved and it is. most probable that the iron of the sheet-iron proper is not attacked and that only the iron in the thin layer of iron-zinc alloy between the zinc coating and the sheetmetal proper is dis-.

solved by-the actionof this basic solution. It may be said that when such a neutral or basic solution is employed as the solvent of zinc only about four-tenths of one per cent. of iron will be dissolved, that is, only one percent. when calculated with respect to the solution, this amount being only onefifth to one-seventh of that which is dissolved in practising the acid processes of removing zinc from zinc scrap employed up to the present time, That the main body of the'iron, as distinguished from'thezinciron alloy in the sheet-metal. is not attacked bythe action "of such a neutral or b sip solvent of zinc is also clearly indicated y the fact that the, process of. recovering zinc from zinc scrap when such a solution 1s used may be carried out in iron vessels or tanks importance, for in carrying out the process on a'coinmercial scale this process has avery considerable advantage over the old process otrecovermg zinc by means of acid solutions, which processes it Was impossible to carry out in iron vessels or tanks becausev the acid solution was a solvent of iron and readily attacked it.

In order that the process may be fully understood the following description is given of the manner in which it .is usually practised. The Zinc scrap or other zincooat-ed material is usually first put into perforated drums; \Vhile in these it is cleaned, it necessary, to remove non-metallic foreignmatter. It may also. be subjected to a process of removing the solder therefrom, which may be done by heating it up to a temperature suflicient to cause the solder to run. iilechanical motion may also be employedin connection with this heatingto facilitate the When in proper removal of such solder. condition the zinccoated material is placed in the dezincing solution. as used in practice, is best composed in such away as to contain, say, about twenty-four parts by weight of Zinc to about twenty-five parts of chlorin instead of the theoretical amount of chlorin, which is a little over twenty-six parts. This basic zinc-containing de-zincing solution is usually heated and is preferably maintained at or above boiling, and each drumcontaining the zinccoated material is preferably rotated in the bath until the ebullition of hydrogen due to the reaction upon and dissolving of the zinc entirely ceases. It is advantageous to employ such an amount of the solvent that at the end of the reaction the solution will have a basicity of from two to three per cent, according as the'material contains a. smaller or a greater amount of Zinc. The solution resulting from the employment of such a reagent is in such a condition as to permit the iron present, Which is in the form of protochlorid of iron, to be precipitated readily. This may be accomplished by any proper means, oXidization by means of chlorate of sodium or chlorid of lime being usually effected. After each operation a part of the bath is permitted to flow" ofl? and to the remaining portion is added such an amount of hydrochloric acid and waslr,

water that the resulting solution has a basicity of about one per cent. and contains about 2% per cent. of zinc. acid (and wash-water) the solution is regenerated and is made ready for immediate use for dezincing another charge.

\Vhen the process of removing the zinc from the :ainc coated material is finished the drums with their contents are lifted out of the bath and are washed one or more timesis removed from the This solution,

jecting said material tothe action of a liquid By the addition of this of chlorid of zinc still adhering to the scrap.

.These washing baths are generally used to fill up the de-zincing solution, but they may be evaporated, precipitated or used in any other Way. 1. For the purpose of illustrating .hoW the process is practised commercially" the fol lowing will serve as "an example: Adi-um containing about one ton of zinc-coated ma-] terial (which in turn-has an average zinc content'of about 10 per cent), is placed in a. bath of 6 cubic 'metersofa s'olution'of chlorid of zinc containing about '24 per cent. of zinc-to about 25 per cent. of chlorin.

That is to 1 say, the solution will" have a.

basicity of about one. per "cent. The reaction is permittedto proceed until the zinc material, when i the solution will ordinarily have a basicity of about three per cent. In order to restore it to its original condition or toaa condition in which it is capable of removing zinc again from scrap, from commercial hydrochloric acid are added to the bath. I

, What- I claimisz. L The process of removing. zinc. from zinc-coated material, which consistsin subjecting said material to the action of a; solvent of zinc which has no a'cidreaction:

350 to 400 kilos of- The process of'removing Zinc from zinc-coated material, which consists subsolvent of zinc which has no acid reaction;

5. The process of "removing. zinc lfromzinc-coated material, which consists in sub-' jecting said material to the action of a'liq? uid zinc-containing solvent ofyzincwhich has no acid reaction." I y 4-. The process of removing zinc from zinc-coated -mater1al which. consistsv in subjecting said material to the action of a basic solvent of. zinc. a

5. The process ofremoving zinc from "zinc-coated mate'r1al, which consists in subjecting said material to'the action'hf a solus tion of chlorid'of zinc which has no'acid reaction," r I ,l 1'

Y 6. The process of removing-Zine from zinc-coated material, which consistsiin subjecting'said material to the action of-a basic solution of chlorid'of zinc. i

7.;"A process of remov ng zinc from zinc' coated iron, which consists in subje'ctingsaid material to the-action of a solvent of zinc j which is substantially not a solvent of iron.

S. A process of removing-zinc from zinccoated iron, which consists in subjecting said u-iaterial to the action of a liquid solvent of zinc which is substantially not a solvent of iron.

9. A process of removing zinc from Zincoatcd iron, which consists in subjecting said material to the action of a zinc-containing ado are

are

solvent of zinc which is substantially not a solvent of iron. I

10. A'process of removing zinc. from zinccoated iron, which consists in subjecting said material to the action of a liquid zinc-containing solvent of zinc which is substantially not a-solvent-of iron. j

11. A process of removing zinc from zinccoated iron,- which consists in' subjecting said material toithe action of a liquid solvent of zinc which is substantially not'a solvent of iron and which has no acid reaction.

12. A process of removing zinc from zinccoated iron, which consists in subjecting said material to the action of a .basic liquid solvent of zinc which is substantially not a solvent of iron.

vent of zinc which has no acid reaction, and

reducing the resultingbasicity of said solvent to fit it for re-use.

14. The process of removing zinc from. .zmc-coated material, which consists in subjecting said material to the action of a-basic solvent of zinc, and reducing the resulting basicity of said solvent to fit it for re-use.

151 The process of removing zinc from zinc-coated iron which consists in sub ecting said material to the action of a basic .solvent of zinc, and precipitating any iron present said material to the action of a basic solvent of -zinc, and subjecting any iron present in the resulting basic solution to direct oxidization.

l7. The process of removing zinc from zinc-coated iron, which consists in subjecting i said material in an iron vessel to theyaction of a basic solvent of zinc which does not attack the iron of said vessel.

18. The process of removing zinc from zinc-coated material which consists in subjecting said material to the action of a solution of zinc chlorid containing about 24: per cent. of Zinc to about 25 per cent.- of chlorin- In witness whereof I have hereunto setmy hand in-the presence of two Witnesses. v

J OSEF WEBER. [L. s.]

Witnesses OTTO KoNIo, CHAS. J. VVRIGHT. 

